michaelle leiter was the counter terrorism director under president george w. bush. >> you can't protect all of the people at all of the large sporting events or any public gathering. that's the advantage terrorists have. they can look for the softest, least defended area. >> it is not unusual to see trash bins removed, mailboxes removed, even the manhole covers screwed down. that's the kind of extraordinary security you get in a presidential zone. putting in place that kind of security at an outdoor marathon, brian, would be a different matter. >> again, how ironic this happened at what was perhaps the most secure zone in all of boston along those 26 miles today. tom costello from washington tonight. tom, thanks. >>> we'll take another break. when we come back, an eyewitness to today's bombing. [ male announcer ] this is kevin. to prove to you that aleve is the better choice for him, he's agreed to give it up. that's today? [ male announcer ] we'll be with him all day as he goes back to taking tylenol. i was okay, but after lunch my knee started to hurt again.